1. Field of the Invention
The present invention relates to nanowires, and more particularly, to nanowire manufacturing. The present invention also relates to the production of high density, high numbers of nanowires.
2. Background of the Invention
Nanomaterials possess very unique and highly desirable properties in terms of their chemical, structural and electrical capabilities. However, to date, there is very little technology available for integrating nanoscale materials into the macroscale world in a reasonable commercial fashion. Depending on application, nanowires may need to be substantially straight, oriented nanowires, such as those used in electronic circuits. In certain cases, however, uses of nanowires have been proposed that exploit the unique and interesting properties of these materials more as a bulk material (e.g., produced in grams or kilograms of material) than as individual elements requiring individual assembly.
Bulk nanowires have enormous potential in electrical, mechanical, and electro-mechanical applications. For example, bulk nanowires can be used to make coatings for medical devices and as catalyst supports in fuel cell applications. A major impediment to commercializing devices using bulk nanowires is the ability to mass produce the nanowires used in such devices.
Nanowires have been grown in chemical vapor deposition (CVD) furnaces primarily on glass and silicon wafers. Methods for increasing the quantity of nanowires grown per volume of furnace have focused on nanowires grown from powders, such as carbon black particles, using a fixed or fluidized bed and column approach. While powders provide a large surface area for nanowire growth, the particles may spill out of the column, and the precursor gases used may not flow uniformly through the column. In addition, non-uniform gas flow may cause silicon deposits to form on the particles, thereby causing the particles to stick together, leaving little space on the particles for nanowire growth.
What are needed are apparatus and methods to efficiently manufacture a high density and high number of nanowires in a given growth chamber volume, using a minimal amount of precursor gas. The present application satisfies these and other needs, and provides further related advantages, as will be made apparent by the description of the embodiments that follow.